Thin keypad assemblies and components for electronics devices and methods

ABSTRACT

A keypad assembly, the keypad assembly including a keycap layer  110  having multiple user interface key caps flexibly coupled to a carrier portion, a luminescent layer  120  disposed toward a backside of the plurality of key cap layer, the luminescent layer carrying a plurality of switch domes aligned with a corresponding one of the plurality of key caps of the key cap layer. In some embodiments, a backing material is applied to a backside of the user interface keycaps.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a division of commonly assigned and U.S.application Ser. No. 10/871,664 filed on 18 Jun. 2004 now U.S. Pat. No.7,070,349, from which benefits under 35 U.S.C. 120 are hereby claimedand the subject matter of which is incorporated herein by reference.

FIELD OF THE DISCLOSURE

The present disclosure relates generally to input devices, and moreparticularly to keypad assemblies and keypad components, for example,keypad assemblies and components for use in super-thin applications, forexample, in wireless communications devices, and corresponding methods.

BACKGROUND OF THE DISCLOSURE

In the past, keypads on cellular radiotelephones have comprised amulti-layered structure having a large part count and that is relativelythick, thus limiting in the thinness of the devices in which the keypadmay be integrated. Typical keypads include user interface forming useraccessible key caps, which are sometimes interconnected by a web. Thekey caps are each aligned over a corresponding switch-dome mounted on acarrier made of Mylar or some other carrier material. The carrier anddome assembly is disposed on a switch contact circuitry layer.

To provide keypad lighting, it is known to dispose a luminescent layerbetween the dome carrier and the key caps. The luminescent layer howeverincludes cutouts through which plunger portions of the key caps maycontact the domes to actuate switches on the circuit layer. Thisconfiguration lacks luminescence directly below or behind the key capswhere it is desired most. Instead, the key caps are lighted indirectlyby dispersed light, some of which emanates from circumferential areassurrounding the keys.

The various aspects, features and advantages of the disclosure willbecome more fully apparent to those having ordinary skill in the artupon careful consideration of the following Detailed Description thereofwith the accompanying drawings described below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exemplary keypad assembly.

FIG. 2 is an exemplary key cap layer.

FIG. 3 is another exemplary key cap layer.

FIG. 4 is an exemplary key cap layer fastening tab.

FIG. 5 is an exploded view of an exemplary key cap layer assembly.

FIG. 6 is an exploded diagram of an exemplary switch-dome/luminescentlayer.

FIG. 7 is an exemplary luminescent layer having colored portions.

FIG. 8 is a sectional view of a potion of an exemplary keypad assembly.

FIG. 9 is a sectional view of portion of another exemplary keypadassembly.

DETAILED DESCRIPTION

FIG. 1 illustrates an exploded view of an exemplary keypad assembly 100comprising generally a user interface keycap layer assembly 110, aswitch-dome/luminescent layer assembly 120 and a keypad circuitry layer130. The exemplary keypad assembly 100 and variations thereof, whichwill become more apparent from the discussion below, have applicationsin handheld electronics devices, for example, in calculators, personalorganizers, personal digital assistants, wired and wirelesscommunications devices including cellular telephones, and portablecomputing machines, among other devices.

The exemplary key cap assembly layer 110 comprises generally a key caplayer having a plurality of user interface key caps flexibly coupled toa carrier or carrier portions. FIG. 5 illustrates an exemplary key caplayer 510. In one embodiment, each key cap is flexibly coupled to thecarrier along at least one side of the key cap, and other remainingsides of the key cap are separated from other key caps and/or carrierportions by a space, thereby allowing the key caps to flex in responseto a tactile depressing action by a user. In another embodiment, each ofthe plurality of user interface key caps are coupled to the carrier by aflexible carrier portion disposed along not more than one side of thecorresponding user interface key cap, wherein other sides of each of theuser interface key caps separated from neighboring key caps and/orcarrier portions by a space.

FIG. 2 illustrates an exemplary key cap assembly layer 200 viewed fromthe user interface side thereof. The exemplary keypad assembly layer 200includes a plurality of key caps, for example, the “7” key cap 210, the“0” key cap 212 and the “9” key cap 214 flexibly coupled by intermediatecarrier portions 211 and 213. FIG. 2 also illustrates space betweenadjacent key caps and between key caps and carrier portions. Forexample, there is space 220 between key cap 210 and the “*” key cap 216.The same space 220 separates key cap 216 from the carrier portion 211.In FIG. 2, at least some of the plurality of key caps and some of thecarrier portions form a unitary member, for example, key caps 210, 212,214 and carrier portions 211 and 213.

FIG. 3 illustrates another exemplary key cap assembly layer 300 viewedalso from the user interface side thereof. The exemplary keypad assemblylayer 300 includes a plurality of key caps, for example, the “7” key cap310, the “0” key cap 312, and the “9” key cap 314 flexibly coupled tointermediate carrier portions 311 and 313. The key cap assembly layer ofFIG. 3 is distinguished from that of FIG. 2 by a carrier portion orportions 316 and 318 along lateral sides of the plurality of userinterface key caps. The exemplary lateral carrier portions 316 and 318interconnect all of the rows of key caps, for example, the rowcontaining key caps “1”, “5” and “3” and the row containing key caps“4”, “8” and “6”, thereby forming a unitary member comprising theplurality of key caps and carrier portions. FIG. 3 also illustratesspaces between adjacent key caps and between key caps and the carrierportions. For example, there is space 320 between key cap 310 and thenumeral “4” key cap 322. The space 320 also extends between key cap 310and the carrier portion 316.

FIG. 5 illustrates an exploded view of an exemplary key cap assemblylayer 500 comprising a key cap layer 510, and a flexible web 520 appliedto a backside of the key cap layer. In one embodiment, the key cap layerincluding the plurality of user interface key caps flexibly coupled tothe carrier is formed from a single sheet of material, for example,stainless steel, or aluminum, or phosphor bronze, or copper alloy orsome other suitable metal material. In one exemplary embodiment, the keycap layer is grade SS304 stainless steel. In other embodiments, the keycap layer is formed of a synthetic or composite material with suitablerigidity and flexibility characteristics. In some embodiments, theplurality of key caps are defined by forming the spaces in a stampingprocess or in some other material removal process, for example, bychemical or laser etching, high velocity fluid cutting, etc. In otherembodiments, the key caps are formed in a molding or casting or someother fabricating process. In one embodiment, the key cap layer is notmore than 1.5 mm thick, and in an exemplary super-thin keypadapplication the key cap layer is between approximately 0.2 andapproximately 0.3 mm thick. These exemplary ranges however are notintended to be limiting. Other exemplary ranges are discussed below.

In FIG. 1, the exemplary key cap assembly layer 110 comprises aplurality of fastening tabs protruding from the side portions of the keycap layer. FIG. 4 is a more detailed view of an exemplary fastening tab400. The fastening tab 400 includes a first flange 410 extending from alateral carrier portion 404 of the key cap, and a second flange 420extending from the first flange. The fastening tab is preferably formedunitarily with the key caps and the carrier from a single sheet ofmaterial, though in other embodiments the fastening tabs may be appendedby some fastening means. FIG. 4 illustrates a bent corner portion 412between the first flange and the second flange.

In some embodiments, the corner portion 412 is formed along a thinnedportion 414 of the sheet material from which the fastening tab isfabricated. The thinned portion 414 facilitates formation of the cornerportion and may be formed by etching or some other process. FIG. 4 alsoillustrates a corner portion 416 between the lateral carrier portion andthe first flange 410. In one embodiment, the corner portion 416 isthinned to facilitate bending and to provide continuity of an edgeportion 402 along the lateral carrier portion 404. Unlike conventionalkey pad assemblies that must be installed from the inside of electronicsdevice housings, keypad assemblies comprising the exemplary key caplayers disclose herein may be installed from the outside of the devicehousing, and be fastened to the housing by the fastening tabs.

In some embodiments, the flexible portion of the carrier flexiblycoupling the plurality of user interface key caps to the carrier portionis relatively thin compared to other portions of the carrier and/or keycaps. In FIG. 3, for example, the carrier portion 330 between key caps“1” and “5” has reduced thickness to provide increased flexibility. Theamount of any required carrier thinning is dependent many factors,including, among others, the thickness and rigidity of the sheetmaterial from which the carrier and key caps are formed, desired tactileperformance, etc. In one embodiment, the thinned carrier portion isformed by etching or by some other material removal process applied tothe surface of the sheet material from which the key cap layer isformed.

In one embodiment, a flexible web interconnects at least some of theplurality of user interface key caps. The flexible web generally bridgesthe space between the plurality of user interface key caps and the spacebetween the key caps and any carrier portions, for example, lateralcarrier portions 316 and 318 in FIG. 3. The flexible web generallyprevents debris from entering into the space between the keycaps, and insome embodiments forms part of the exterior of the key cap layer.

In one embodiment, the flexible web interconnecting the plurality ofuser interface key caps comprises a material different than the materialof the user interface key caps. In one exemplary embodiment, theflexible web is a resilient material, for example, silicone. Moregenerally, in other embodiments, the flexible web may be some otherelastomer material. In one embodiment, the flexible web is formed of atranslucent material that permits emanation of backlighting fromluminescent layer, which is discussed further below. The flexible webmay be clear or tinted to provide contrast relative to the key caps. Insome embodiments, the flexible material is doped with the materials toprovide special effects, and/or it may be coated with ink or othercoloration.

FIG. 5 illustrates the exemplary key cap assembly layer 500 comprisingthe key cap layer 510 discussed above, and a flexible web 520 applied toa backside of the key cap layer. The exemplary flexible web 520 may bemolded, for example, injection molded or insert molded or otherwisedeposited on the backside of the key cap layer. In one embodiment, theflexible web material protrudes into the space between key caps and anycarrier portions, and in some embodiments the flexible web forms part ofthe visible exterior of the key cap layer. In FIG. 5, the exemplaryflexible web 520 is applied largely to the carrier and partly to the keycaps, leaving portions of the key cap exposed for the application ofanother backing material discussed further below.

In other embodiments, the flexible web may be a flexible web filmdisposed over or applied to an outer surface of the key cap layer. Inanother alternative embodiment, the flexible web and the plurality ofuser interface key caps comprise a common material forming the unitarymember. According to this alternative embodiment, the flexible web isformed from the sheet material from which the key cap layer is formed.In one embodiment, the flexible web portions between key caps and anycarrier portions is formed by reducing the thickness of portions of thesheet material, for example, by etching. In this embodiment, the removedportion of the sheet material forms the space between individual keycaps, and the reduced thickness portion of the sheet material also formsthe flexible web bridging the space.

In one exemplary key cap layer assembly, a backing material is disposedon the backside of corresponding key caps. In some embodiments, thebacking material provides rigidity for the key caps, particularly inapplications where the key cap is relatively thin and also inembodiments where the key cap material is insufficiently rigid toprovide the desired tactile performance. In the exemplary embodiment ofFIG. 5, backing material portions 530 are disposed on corresponding keycaps of the key cap layer 510, for example, backing portion 502 isapplied to key cap 512.

In some embodiments, the backing material is different than the materialconstituting the flexible web. For the example, the flexible web may bea relatively resilient or elastic material and the backing material maybe a relatively rigid or hard material. In one exemplary embodiment, thebacking is a TOYOLAC 900 Series material. In some embodiments, thebacking material is doped with materials to provide special effects,and/or it may be coated with ink or other coloration.

In one exemplary application process, the backing material is applied toa backside of a plurality of key caps, for example, keycaps flexibleinterconnected by a carrier portion. In embodiments where multiple userinterface key caps are flexibly coupled to one or more carrier portions,a flexible web is applied to the backside of the key cap layer. In oneembodiment, the flexible web is applied to the backside of the key caplayer. The flexible web may be applied by any application procedure, forexample, an insert molding process. In an alternative embodiment, theresilient material is applied to the key cap first, so that theresilient material forms a wall portion surrounding the portion of thekey cap where the backing material is desired. The backing material isthen applied to the portion of the key cap surrounded by the resilientmaterial wall portion, wherein the resilient material wall portioncaptures the backing material applied to the key cap. In anotheralternative embodiment, the backing material is part of the flexible webdisposed on the backside of the key caps.

In some embodiments, some or all of the key caps have artwork disposedthereon for indicating functionality and/or for providing otherinformation associated with the corresponding key cap. The artwork maybe printed or imprinted on the key caps. In other embodiments, embossedor intaglio artwork is applied to the key caps, for example, to a homekey like the “5” key, or to all of the key caps to provide a tactileinterface.

The exemplary key cap layers 200 and 300 of FIGS. 2 and 3 comprise keycaps including artwork apertures. The exemplary artwork aperturesinclude alphanumeric characters and other functional symbols suitablefor use in a communications device application. In some embodiments, thekey cap backing material covers or fills the artwork aperture. In oneembodiment, the backing material is a clear or tinted translucentmaterial that permits light to emanate from a luminescent layer disposedbelow the key caps as discussed further below. According to a relatedaspect of the disclosure, the backing material disposed in the artworkaperture may be used to capture portions of the artwork that wouldotherwise require support structure or be susceptible to dislodgement.These captured artwork portions include, for example, the centerportions of the numerals “0”, “4”, “6”, “8” etc. A tactile interface maybe formed on some or all of the key caps as discussed above or byallowing some of the backing material to protrude through the artworkaperture beyond the surface of the key cap. The tactile interface mayalso be produced by embossing or by an intaglio process.

According to another process for making the key cap layer assembly, keycap function or identification artwork is etched in a relatively thinmetal sheet, for example, a thickness between 0.2 mm and 0.3 mm. Then ahard translucent plastic material is molded to a backside of the metalsheet where the key caps will be defined. Next, the key cap perimetersare etched in the thin sheet. And then the flexible web is formed aroundthe key cap perimeter, as discussed above. The flexible web allows thekey caps to move independently, and it also prevents the key caps frombeing pulled up. As a final step, the key caps may be subject tofinishing operations to polish the cosmetic surface and/or to removeexcess molded in material from the key cap layer.

In FIG. 1, the switch-dome/luminescent layer 120 comprises a luminescentlayer, for example, an electro-luminescent layer. In the exemplaryembodiment, the luminescent layer functions as a carrier for an array ofswitch-domes aligned with corresponding key caps of the key cap layer.FIG. 6 is an exploded diagram of an exemplary switch-dome/luminescentlayer assembly 600. The exemplary assembly comprises a luminescent layer610. In one embodiment, the luminescent layer 610 is anelectro-luminescent layer, for example, the Durel DFLX-665 flexibleelectro-luminescent lamp manufactured by Rogers Corporation, DurelDivision, Chandler, Ariz. In other embodiments, the luminescent layermay comprise other luminescent materials.

In one embodiment, the luminescent layer is colored or tinted to providecolored backlighting. In FIG. 7, the exemplary luminescent layerincludes a green colored or tinted portion 702 and a red colored ortinted portion 704. The exemplary green and red colored portions may belocated behind ON or SEND keys and OFF or END keys, respectively. Inother embodiments, other colors may be used on these and other keys.

FIG. 6 also illustrates an adhesive layer 620, for example, ascreen-printed adhesive, which is adhered to a side of the luminescentlayer 610. Also included with the switch-dome/luminescent layer is anarray of switch domes 630 adhered to the luminescent layer 610 by theadhesive layer 620 in alignment with the corresponding key caps.Alternatively, the domes 630 may be adhered to the luminescent layer 610by discrete amounts of adhesive, without the requirement for theexemplary adhesive layer. In other embodiments, the switch-domes may becoupled to the luminescent layer by some other fastening means. Carryingthe domes on the luminescent layer eliminates the need for the dedicatedcarrier, e.g., the Mylar layer, used in conventional designs.

In the exemplary embodiment, the switch-domes array 630 is adhered to abackside of the luminescent layer 610 by the intermediate adhesive layer620. In one embodiment, the luminescent layer is a pliable material thatconforms about the domed surface of the switch dome, thereby ensuringsufficient adhesion with the adhesive layer. In an alternativeembodiment, the domes may be disposed between the luminescent layer andsome other layer. Locating the switch-domes on the backside of theluminescent layer ensures that light emanates from the luminescent layerdirectly behind the key caps. In an alternative embodiment, theswitch-domes are disposed on a front-side of, or atop, the luminescentlayer. The use of a clear or translucent switch-dome will reduce anyobstruction, by the dome, of light emanating from directly behind thekey caps. In the exemplary embodiment, the switch-domes include a nipple632, which provides good tactile performance by ensuring that the domesweet spot is actuated. In other embodiments, the protrusion may belocated in or on the backing material disposed on the key caps.

In alternative embodiments, the luminescent layer includes cutoutportions that accommodate the switch-domes or portions thereof, therebyreducing the thickness of the assembly resulting from layer stacking. Inother embodiments, a conventional carrier layer, for example, a Mylarlayer, carries the switch-domes. The switch-domes carrier layer ispositioned so that the domes adhered or otherwise fastened thereto arealigned with corresponding switches on a keypad circuitry layer. In FIG.1, the exemplary luminescent layer dome carrier 120 is positioned tothat the plurality of switch-domes, e.g., domes 122 and 124, disposedthereon are positioned over corresponding switches, e.g., switch 132 and134, on the circuitry layer 130. The resulting assembly of the keypadlayer assembly 110, the switch-dome/luminescent layer 120 and thecircuitry layer provides for a relatively compact keypad assembly havingan overall thickness between approximately 1.0 mm and 5.0 mm.

In FIG. 8, a sectional portion of an exemplary keypad assembly 800comprises an exemplary keypad assembly incorporating features discussedabove. The section portion of FIG. 8 corresponds, for example, to asection through the directional cursor controller 230 and selection key232 in FIG. 2. A key cap layer 802 includes a selection key cap 803 anda directional cursor controller input 805 corresponding to the selectionkey 232 and cursor controller 230 of FIG. 2. The exemplary key cap layeris approximately 0.15 mm and includes a surface coating 806, forexample, Urethane. The selection key cap includes an artwork aperturefiled with a translucent material 805 to permit the passage of lightfrom a backlight source, discussed below. A base film 810, which ispreferably transparent, is co-molded between top and bottom siliconefilms 812 and 814, respectively. The key top layer is adhered to thebase film by a glue layer 816. A luminescent layer 820 functions as adome carrier. An exemplary dome 822 is located below the key cap 803. Aplunger 824 is disposed between the key cap 803 and the dome 822. Theplunger may be a part of, or attached, to the dome or to structureopposite the dome. The overall thickness of the exemplary keypad layeris less than approximately 1.2 mm.

In FIG. 9, another exemplary keypad assembly 900 comprises a key caplayer including a first key cap 902 and a second key cap 904. A flexibleweb portion 906 is disposed between adjacent key caps 902 and 904 andother neighboring key caps. A backing material 908 is disposed on abackside of key cap 902 and protrudes through an artwork aperture in thekey cap, as illustrated. A plunger 912 is formed integrally with thebacking material a switch-dome below the key cap 902. A luminescentlayer 920 is disposed below the key cap layer assembly. The exemplaryluminescent layer 920 functions as a carrier for switch-domes 922, whichare adhered thereto by an intermediate adhesive layer 924, as discussedabove. The luminescent layer and switch-domes are disposed on a circuitboard 930, which is mounted in a housing 940.

While the present disclosure and what the best modes of the inventionshave been described in a manner establishing possession thereof by theinventors and enabling those of ordinary skill in the art to make anduse the same, it will be understood and appreciated that there are manyequivalents to the exemplary embodiments disclosed herein and thatmodifications and variations may be made thereto without departing fromthe scope and spirit of the inventions, which are to be limited not bythe exemplary embodiments but by the appended claims.

1. A keypad assembly, the keypad assembly comprising: a plurality of keycaps flexibly coupled to a carrier portion, the plurality of key capshaving a user interface side and a backside, the plurality of key capsand the carrier portion constitute a substantially planar unitarymember, the plurality of key caps defined by slots through the unitarymember, the slots devoid of material from which the plurality of keycaps and the carrier are formed, no portion of the carrier portionextending into the slots between adjacent key caps; a resilient materialbridging the slots between the plurality of key caps; a luminescentlayer disposed toward the backside of the plurality of key caps, theluminescent layer carrying a plurality of switch domes, the plurality ofswitch domes each aligned with a corresponding one of the plurality ofkey caps.
 2. The keypad assembly of claim 1, the luminescent layerdisposed between the plurality of switch domes and the plurality of keycaps flexibly coupled to the carrier portion.
 3. The keypad assembly ofclaim 2 further comprising, a keypad circuitry layer, the luminescentlayer disposed between the keypad circuitry layer and the plurality ofkey caps flexibly coupled to the carrier portion, the plurality ofswitch domes disposed between the keypad circuitry layer and theluminescent layer.
 4. The keypad assembly of claim 2, the resilientmaterial is a translucent material.
 5. The keypad assembly of claim 2further comprising, a backing material disposed on a backside of atleast some of the plurality of key caps.
 6. The keypad assembly of claim2, at least one of the plurality of key caps includes an artworkaperture.
 7. The keypad assembly of claim 6, the artwork aperturecovered by a translucent material.
 8. The keypad assembly of claim 1,the plurality of key caps defined by and located between nested slotsformed through the unitary member.
 9. The keypad assembly of claim 8,the nested slots having a substantially serpentine configuration.
 10. Akeypad assembly, the keypad assembly comprising: a user interface layerincluding a plurality of key caps flexibly coupled to a carrier portion,the plurality of key caps defined by slots through a unitary member, theslots devoid of material from which the plurality of key caps and thecarrier portion are formed, the plurality of key caps and the carrierportion constituting the unitary member; a resilient material bridgingthe slots between the plurality of key caps, the resilient materialhaving a different flexibility characteristic than the material fromwhich the plurality of key caps and the carrier are formed; aluminescent layer disposed below the user interface layer, theluminescent layer carrying a plurality of switch domes on one sidethereof, the plurality of switch domes each aligned with a correspondingone of the plurality of key caps of the user interface layer.
 11. Thekeypad assembly of claim 10, the luminescent layer disposed between theplurality of switch domes and the key caps of the user interface layer.12. The keypad assembly of claim 10 further comprising, a keypadcircuitry layer, the luminescent layer disposed between the keypadcircuitry layer and the plurality of key caps flexibly coupled to thecarrier portion, the plurality of switch domes disposed between thekeypad circuitry layer and the luminescent layer.
 13. The keypadassembly of claim 10, the plurality of key caps defined by and locatedbetween nested slots formed through the unitary member.
 14. The keypadassembly of claim 13, each nested slot having a substantially serpentineconfiguration.
 15. A keypad, comprising: a plurality of user interfacekey caps flexibly coupled to a carrier, the plurality of user interfacekey caps defined by voids formed in a unitary member, the voids devoidof material from which the plurality of user interface key caps and thecarrier are formed; a flexible web bridging the voids between theplurality of user interface key caps, the plurality of user interfacekey caps, the carrier and the flexible web constitute the unitarymember; a luminescent key caps disposed below the plurality of userinterface layer, the luminescent layer carrying a plurality of switchdomes on one side thereof, the plurality of switch domes each alignedwith a corresponding one of the plurality of user interface key caps.16. The keypad of claim 15, a portion of the luminescent layer disposedbetween the plurality of switch domes and the plurality of userinterface key caps.
 17. The keypad of claim 15, the plurality of userinterface key caps defined by and located between two nested voidsformed in the unitary member, each of the nested voids having asubstantially serpentine configuration.